The cheapest raised beds use untreated wood and materials you may already have
A basic raised bed costs between $20 and $50 to build, depending on the size and what you already own. The fastest route is to buy untreated lumber boards, a drill, and wood screws—then assemble a frame in an afternoon. If you have scrap wood, cardboard, or old pallets on hand, you can build one for almost nothing.
The key to staying cheap is avoiding treated wood (which costs more and can leach chemicals), buying lumber in standard sizes so you don't pay for cutting, and skipping the fancy hardware. A 4-by-8-foot bed that holds enough soil for vegetables costs roughly $30 to $40 in materials if you buy new wood, or under $10 if you use what you have.
Key Takeaways
- Untreated pine or cedar boards are cheaper than treated lumber and safe for vegetables; buy them in standard lengths like 8 feet to avoid cutting fees.
- A 4-by-8-foot bed needs four boards, wood screws, a drill, and a level—total cost around $35 if you buy everything new.
- Scrap wood, old pallets, stacked cardboard, or concrete blocks can replace lumber entirely and bring the cost to nearly zero.
- Line the bottom with cardboard to kill grass and weeds, then fill with soil; this step saves money by preventing weed growth later.
- Assemble on level ground and check corners with a square before filling, because a crooked bed wastes soil and looks uneven.
Buying lumber and hardware for a basic frame
Start at a home improvement store or lumber yard and ask for untreated pine or cedar boards in 8-foot lengths. A 4-by-8-foot bed needs four boards: two that are 8 feet long and two that are 4 feet long. If the store will cut them for free, ask them to cut two of the 8-foot boards to 4 feet. If they charge, buy two 8-foot boards and one 4-foot board, then ask a friend with a saw to cut one 8-footer in half—it takes two minutes.
Buy a box of 2.5-inch wood screws (about $5 to $8) and a power drill if you don't own one (borrow from a neighbor or rent from a tool library for $5 to $10). You will also need a level (borrow one if possible) and a carpenter's square to check that corners are 90 degrees. The total for a new bed is roughly $30 to $40.
Avoid pressure-treated lumber, which costs more and can release chemicals into soil over time. Cedar and pine are naturally rot-resistant enough for a raised bed that will last five to seven years. If you want it to last longer, cedar costs more upfront but resists rot better than pine.
Using scrap wood, pallets, or cardboard instead
If you have old fence boards, deck scraps, or leftover lumber from a project, use those. Stack them to the height you want (usually 12 inches for vegetables), then screw or nail them together at the corners. The boards don't have to match in width or color—a mismatched bed works just as well and costs nothing.
Wooden pallets are free or very cheap at warehouses, garden centers, or on the side of the road. Remove any nails, stack four pallets into a square, and screw them together at the corners. A pallet bed is usually about 4 feet square and takes 30 minutes to assemble. Check that the pallets were not treated with chemicals (look for "HT" stamped on the wood, which means heat-treated and safe; avoid "MB," which means methyl bromide).
Cardboard works as a temporary bed and costs nothing if you save boxes from deliveries or ask a grocery store for produce boxes. Stack them 12 inches high, overlap the seams, and fill with soil. The cardboard breaks down in one to two seasons, so this method works best as a test bed before you invest in wood. Layer cardboard on top of grass under any bed to kill weeds and prevent them from growing up through the soil.
Assembling the frame step by step
Lay the four boards on level ground in a rectangle. Use a carpenter's square to check that each corner is 90 degrees—if the corners are off, the bed will lean and soil will spill out. Adjust the boards until the square fits snugly in each corner.
Drill two pilot holes (small holes that guide the screw) at each corner, then drive a 2.5-inch screw through each hole. Drill from the outside of the bed so the screw head sits flush or slightly below the surface. Two screws per corner is enough for a bed up to 8 feet long; if you build a longer bed, add a third screw in the middle of each long side.
Check the bed with a level in both directions—front to back and side to side. If one corner is higher than the others, dig out soil under the low corners or add soil under the high corners until the bed is level. A level bed drains evenly and looks finished.
Preparing the ground and lining the bottom
Clear grass and weeds from the area where the bed will sit. You don't have to dig deep—just pull up the biggest weeds and break up the soil with a shovel. If the ground is very compacted, loosen the top 4 inches.
Lay cardboard over the entire bottom of the bed, overlapping the seams by at least 6 inches. Wet the cardboard so it stays in place, then poke holes in it with a shovel so water can drain. The cardboard kills grass underneath and prevents weeds from growing up into the bed. It breaks down over one to two years, so you only need to do this once.
If you don't have cardboard, lay down landscape fabric or several layers of newspaper. Avoid plastic, which blocks drainage and can trap water.
Filling with soil and getting ready to plant
A 4-by-8-foot bed that is 12 inches deep holds about 32 cubic feet of soil. Buy bags of garden soil or topsoil (usually 2 cubic feet per bag) and fill the bed until the soil is about 2 inches below the top of the frame. This leaves room for mulch and prevents soil from washing out when you water.
Soil in bags costs more per cubic foot than bulk soil delivered by truck, but it is easier to handle if you are building just one or two beds. If you are building three or more, call a landscape supply company and ask for bulk topsoil or garden soil delivered. Bulk soil usually costs $30 to $50 per cubic yard, which is cheaper per cubic foot than bags.
Mix in compost or aged manure (about one-third compost to two-thirds topsoil) to add nutrients. Let the bed sit for a week before planting so the soil settles. If the soil level drops below the top of the frame after a week, add more soil.
Common mistakes that waste money
Buying treated lumber costs more and is unnecessary for a vegetable bed. Untreated wood is cheaper and safer. Do not use railroad ties or old utility poles, which are treated with creosote and can poison soil.
Skipping the cardboard bottom means weeds will grow up through the bed for years, and you will spend money on weed killer or time pulling them. Cardboard costs nothing if you save boxes and saves money later.
Building on unlevel ground causes one corner to sink and the frame to twist. Check the level before you fill the bed, not after. Fixing a crooked bed after it is full of soil is hard and wastes soil.
Buying soil in small bags for a large bed gets expensive fast. A 4-by-8-foot bed needs 32 bags if you buy 2-cubic-foot bags, which can cost $60 to $80. Bulk soil or a mix of compost and topsoil from a landscape supplier costs less.
Frequently Asked Questions
Can I use treated wood if I seal it?
Untreated wood is cheaper and safer, so there is no reason to buy treated wood and then seal it. Untreated pine or cedar lasts five to seven years, which is long enough to decide if you want to rebuild or upgrade. If you want the bed to last longer, buy cedar from the start instead of pine.
How deep does a raised bed need to be?
Twelve inches is enough for most vegetables like lettuce, spinach, and beans. Root vegetables like carrots and beets need 12 to 18 inches. If you are building on concrete or very hard ground, go deeper so roots have room to grow. Shallow beds dry out faster and need more water.
Do I have to use a carpenter's square?
A square makes sure the corners are 90 degrees, which keeps the bed from leaning. If you don't have one, measure diagonally from corner to corner—if both diagonals are the same length, the corners are square. It takes 30 seconds and saves frustration later.
Can I build a raised bed on top of concrete?
Yes, but you need to go deeper because roots cannot grow into concrete. Build the bed at least 18 inches deep and use landscape fabric on the bottom instead of cardboard (cardboard will rot faster on concrete). Water will sit on concrete instead of draining, so drill drainage holes in the fabric or add a layer of gravel under the soil.
What size bed should I build if this is my first one?
Start with a 4-by-4-foot bed or a 4-by-8-foot bed. A 4-by-4 is easier to reach into from all sides and costs about $20 to build. A 4-by-8 costs about $35 and gives you more space. Avoid beds wider than 4 feet because you cannot reach the middle without stepping in the soil.